Dear all, I ran a small example program, and this is what I got from using the -s flag: 486,550,118,368 bytes allocated in the heap 323,749,418,440 bytes copied during GC 1,842,979,344 bytes maximum residency (219 sample(s)) 204,653,688 bytes maximum slop 4451 MB total memory in use (0 MB lost due to fragmentation) Generation 0: 924208 collections, 0 parallel, 1861.17s, 1866.05s elapsed Generation 1: 219 collections, 0 parallel, 283.44s, 284.01s elapsed INIT time 0.00s ( 0.00s elapsed) MUT time 740.61s (745.45s elapsed) GC time 2144.61s (2150.06s elapsed) EXIT time 0.00s ( 0.00s elapsed) Total time 2885.23s (2895.51s elapsed) %GC time 74.3% (74.3% elapsed) Alloc rate 656,953,176 bytes per MUT second Can anyone tell me what the exact difference is between 1,842,979,344 bytes maximum residency (219 sample(s)) and 4451 MB total memory in use (0 MB lost due to fragmentation) I could not find this information in the docs anywhere, but I may have missed it. best, Jur